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WMO. Press Briefing on the Working Group-II Report of the IPCC Fourth Assessment Report (AR4). Dr R K Pachauri Director-General, TERI & Chair, IPCC April 10, 2007. Direct Observations of Recent Climate Change. Global average air temperature
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WMO Press Briefing on the Working Group-II Report of the IPCC Fourth Assessment Report (AR4) Dr R K Pachauri Director-General, TERI & Chair, IPCC April 10, 2007
Direct Observations of Recent Climate Change Global average air temperature • Updated 100-year linear trend of 0.74 [0.56 to 0.92] oC for 1906-2005 • Larger than corresponding trend of 0.6 [0.4 to 0.8] oC for 1901-2000 given in TAR • Average ocean temperature increased to depths of at least 3000 m – ocean has absorbed 80% of heat added > seawater expansion and SLR
Warmest 12 years: 1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000 50 0.1280.026 100 0.0740.018 Global mean temperatures are rising faster with time Period Rate Years /decade
Proportion of heavy rainfalls: increasing in most land areas Regions of disproportionate changes in heavy (95th) and very heavy (99th) precipitation
Land precipitation is changing significantly over broad areas Increases Decreases Smoothed annual anomalies for precipitation (%) over land from 1900 to 2005; other regions are dominated by variability.
Glaciers and frozen ground are receding Area of seasonally frozen ground in NH has decreased by 7% from 1901 to 2002 Increased Glacier retreat since the early 1990s
Projections of Future Changes in Climate Best estimate for low scenario (B1) is 1.8°C (likely range is 1.1°C to 2.9°C), and for high scenario (A1FI) is 4.0°C (likely range is 2.4°C to 6.4°C). Broadly consistent with span quoted for SRES in TAR, but not directly comparable Source: IPCC
Impacts of observed climate change • Many natural systems on all continents and some oceans affected by regional climate change, rising temperatures • We conclude that warming caused by human activities has likely had a discernible impact on the global level on many physical and biological systems
Temperature changes since 1970 and observed changesin physical and biological systems contd…
Some systems and sectors are very vulnerable • Some ecosystems: • Coral reefs; sea-ice regions • Tundra, boreal forests, mountain and Mediterranean regions • Low-lying coasts, mangroves & salt marshes • Water resources in mid-latitudes & dry Tropics • Low-latitude agriculture • Human health where adaptive capacity is low
Corals will be affected by: • Warmer ocean temperatures leading to bleaching • Ocean acidification leading to shell dissolution
Some regions will be more affected than others • The Arctic • Sub-Saharan Africa • Small islands • Asian megadeltas
North Atlantic thermohaline circulation • Shutdown during 21st century very unlikely • Temperatures will continue to increase this century over Europe and North America, even if the N. Atlantic circulation slows • Large-scale changes projected to affect: • Marine ecosystem productivity • Fisheries • Ocean CO2 uptake
Impacts of extreme weather events are expected to increase • We can understand these impacts by looking at some recent events
Impacts of Climate Change in Asia • Climate change has affected many sectors in Asia • In future likely to affect agriculture, risk of hunger and water resource scarcity with enhanced climate variability and more rapid melting of glaciers • Also, likely to affect forest expansion and migration, exacerbate threats to biodiversity • Multiple stresses in Asia will be compounded further due to climate change
Impact on Agriculture and food security contd… • Substantial decreases in cereal production potential in Asia • Crop simulation modeling studies based on future climate change scenarios indicate, substantial losses are likely in rain-fed wheat in South and Southeast Asia • For e.g. 0.5o C rise in winter temperature would reduce wheat yield by 0.45 tonnes per hectare in India. (Average yield of wheat 2.6 tonnes per hectare in 2006 – Source: GAIN Report)
Impact on Agriculture and food security • Climate Change can affect not only crop production per unit area but also the area of production. • Most of the arable land suitable for cultivation in Asia is already in use • Food insecurity and loss of livelihood to be further exacerbated by loss of cultivated land and nursery areas for fisheries by inundation and coastal erosion in low-lying areas of tropical Asia
Impact on hydrology and water resources contd… • Climate change related melting of glaciers could seriously affect half billion people in the Himalaya-Hindu-Kush region, a quarter billion people in China, depending on glacier melt for water supplies • Unfavorable consequences for downstream agriculture in most countries of South Asia relying on glacier melt for water for irrigation • India, China and Bangladesh are especially susceptible to increasing salinity of groundwater and surface water resources especially along the coast, due to increase in sea level as a direct impact of global warming
Impact on hydrology and water resources • Gross per capita water availability in India will decline from ~ 1820 m3/ yr in 2001 to as low as ~1140 m3/yr in 2050 • The projected decrease in the winter precipitation over Indian subcontinent would reduce the total seasonal precipitation during December, January and February implying lesser storage and greater water stress • Intense rain occurring over fewer days, which implies increased frequency of floods during the monsoon, will also result in loss of the rain water as direct runoff resulting in reduced groundwater recharging potential.
Impact on Coastal and low lying areas • Projected sea level rise could flood the residence of millions of people living in the low lying areas of South, Southeast and East Asia such as in Vietnam, Bangladesh, India and China • Even under the most conservative scenario, sea level will be about 40 cm higher than today by the end of 21st century and projected to increase the annual number of people flooded in coastal population from 13 million to 94 million • Almost 60% of this increase will occur in South Asia (along coasts from Pakistan, through India, Sri Lanka and Bangladesh to Burma)
Impact on natural ecosystems and biodiversity • Up to 50% of the Asia’s total biodiversity is at risk due to climate change • The natural grassland coverage and the grass yield in Asia, in general, are projected to decline with rise in temperature and higher evaporation • More frequent and prolonged droughts as a consequence of climate change and other anthropogenic factors together will result in the increasing trends of desertification in Asia
Impact on human health • Climate change poses substantial risks to human health in Asia • Global burden (mortality and morbidity) of climate-change- attributable diarrhoea and malnutrition are already the largest in South and Southeast Asian countries including Bangladesh, Bhutan, India, Maldives, Myanmar and Nepal in 2000 • The relative risks for these conditions for 2030 is expected to be also the largest • An empirical model projected that population at risk of dengue fever (the estimated risk of dengue transmission is greater than 50%) will be larger in India and China • In India and China, the excess mortality due to heat stress is projected to be very high
Current knowledge about future impacts contd.. Ecosystems • Over the course of this century net carbon uptake by terrestrial ecosystems is likely to peak before mid-century and then weaken or even reverse, thus amplifying climate change. • Approximately 20-30% of plant and animal species assessed so far are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5-2.5oC. Coastal systems and low-lying areas • Many millions more people are projected to be flooded every year due to sea-level rise by the 2080s. Those densely-populated and low-lying areas where adaptive capacity is relatively low, and which already face other challenges such as tropical storms or local coastal subsidence, are especially at risk. The numbers affected will be largest in the mega-deltas of Asia and Africa while small islands are especially vulnerable.
Current knowledge about future impacts Africa • By 2020, between 75 and 250 million people are projected to be exposed to an increase of water stress due to climate change • Agricultural production, including access to food, in many African countries and regions is projected to be severely compromised by climate variability and change. Asia • Glacier melt in the Himalayas is projected to increase flooding, rock avalanches from destabilised slopes, and affect water resources within the next two to three decades • Endemic morbidity and mortality due to diarrhoeal disease primarily associated with floods and droughts are expected to rise in East, South and Southeast Asia due to projected changes in hydrological cycle associated with global warming. Increase in coastal water temperature would exacerbate the abundance and/or toxicity of cholera in South Asia.
Horticulture damage Source: Commissionerate of Horticulture, Government of Andhra Pradesh
Effect of temperature on poultry Birds are comfortable at 18oC to 30oC, RH 55 to 75%
Adaptation will be necessary to address impacts resulting from the warming which is already unavoidable due to past emissions